Diazonium fluosilicates



F'atented July 1, 1947 DIAZONIVUM FLUOSILICATES Richard Haven Wiley, Wilmington, Del., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application July 26, 1945,

' Serial N0. 607,265

. 1 Claim.

This invention relates to diazonium fluosilicates and to a process for preparing them.

This invention has as an object the preparationoi Water-soluble diazonium salts that are stable in the dry state at C. A further object is the preparation of 'diazonium salts from aromatic amine fluosilicates. Other objects will appear hereinafter.

These objects are accomplished by the invention of aromatic diazonium fluosilicates and their preparation by the reaction of a fluosilicate of a primary aromatic amine having an NHz group attached .to aromatic carbon, with ethyl nitrite in an acidic liquid medium and the subsequent isolation of the aromatic diazonium fluosilicate.

In the preferred method of preparing the solid diazonium fluosilicates of this invention, the aromatic amine fiuosilicate is first prepared by addin the amine to an excess of fiuosilicic acid in an aqueous alcoholic'medium, and isolating the precipitated amine salt. The solid amine fluosilicate is then suspended in glacial acetic acid, and ethyl nitrite is added as vapor to the suspension with cooling to keep the reaction mixture below 40 0. As the reaction proceeds, the suspended amine salt first dissolves, and then is reprecipitated as the diazonium fiuosilicate. Diethyl ether is then added to the reaction mixture to complete the precipitation of the diazonium fluosilicate, and the diazonium salt is then filtered,

washed with ether and-alcohol, and dried.

The more detailed practice of the invention is illustrated by the following examples. There are, of course, many forms of the invention other than the specific embodiments.

EXAMPLE I V Benzenediazonium fluosilicate absolute alcohol.

action. Theaqueous solution also gave a precipitate with aqueous barium chloride and with aqueous sodium chloride indicating the presence of fluosilicate ions; The'benzenediazom'um fluosilicate obtained analyzed as follows: calculated for (CsH5N2)2SiF6: N, 15.9%; found, N, 15.7%.

The temperature of decomposition of this compound was determined by heating a small amount in a glass vessel-in an'oil -bath. At 95 C. and at 91 C. a vigorous decomposition'with a slight explosicn' took place'at once. The compound was held at85 C. for ten minutesbefore a less vigorous decomposition occurred 'and'was held one 95% alcohol and dried. The dry salt analyzed as follows: Analysis: calculated for (CsHsNHz) 2H2S1Fs hour at 79-80 C. Without vigorous decomposition.

. ,E'XAMPLEIIVY o-Metho:rybenzenediazonium flu'osilicate Anisidine fiuosilicate was prepared from orthoanisidine and 27% aqueous fluorsilici'c acid in absolute alcohoL The dry salt analyzedfas follows: calcula'ted'for (CH3OC6H4NH2)2H2S1F6{ N, 7.18%; found, N, 6.93%. Anisidine fluorsilicate was also prepared from anisidine by passing gaseous silicon 'tetrafluoride into an alcoholic solution'of anisidine; .Thesalt thus formed contained 6.3% nitrogen. f p

The salt was 'diazotized inglacial acetic'acid suspension-with ethyl nitrite as described in the previous example to'give 'o-methoxybenzenediazonium'fluosilicate. I

The diazonium salt was soluble in water and the aqueous solution coupled with alkaline betanaphthol to give a carmine-colored solid. The aqueous solution also gave a precipitate with both aqueous barium chloride and aqueous sodium chloride indicating the presence of fluosilicate ions. The diazonium salt gave the following analysis: calculated for (o-CH3OCeH4N2)2SiFs:N, 13.6%; found, N, 13.1%.

EXAMPLE HI p-Carbethorybenzenediaeonium fluosz'licate The fluosilicate of ethyl p-aminobenzoate was prepared by adding 27% aqueousfluosilicic acid to a solution of the amine in ethyl alcohol and was recrystallized from an alcohol-water mix 3 ture. The dry salt analyzed as follows: calculated for (C2H502CCsI-I4NH2)zHzsiFstN, 5.92%; Si, 5.92%; found, N, 5.8%; Si, 5.93%.

This salt was diazotized by the procedure described in Example I. The diazonium salt was completely soluble in acetic acid and was precipitated asja'solid by adding ether. The carbethoxybenzenediazonium fluosilicate thus prepared was also soluble in Water. The aqueous solution gave a red precipitate with beta-naphthol in a coupling reaction and gave a precipirtate with barium chloride and aqueous sodium chloride indicating the presence 9f fluosilicate ions. analysis: calculated for (CzI-I OCC'eI-I4N2) zSiFa-z EXAMPLE IV Preparation of p-fluorobenzoic acid from p-carbethoxybenzenedz'azonium fluosilicate Four and five tenths grams of pcarbethoxw benzenediazonium fluosillcate was heated in a re- ;actionvessel undercondenser whereupon a spon taneou' s decomposition withcopious evolution of a.tqol .place. The liquid remaining was .saponifiedwith. aqueous sodium hydroxide and on acidificationof the saponification' mixture 0.3 g". of a solid separated which, after recrystallization from water, hada melting point of 181.2182.2 C. (corrected) andhad a neutral eguivalent of 136.7.

The reported melting point for p-fiuorobenzoic acid is182 C. and thecalculated neutral equivalent .is 140.

EXAMPLE V m-Chlorobenzenediazpnium fluoszlicate The f luosilicate of mrchloroaniline was prepared from mwchloroaniline and 27% aqueous iiuosilicic acid in m ethan,o1 as a solvent. Ethyl nitrite was passed into a suspension of 7.98 g. pftheiiuosilicate in 50 cc. of glacialacetic acid, the temperature being held'at 3 l) -to 35 C. during the diazotization. A solution was obtained which was treated'with decoiorizing charcoal and filtered- Absolute ether was then added until a slight cloudiness formed. and on standing, crystal se ara ed from the .ni tu p eci itated m'-chloroben zenediazonium fluosiliclate was found tobesoliibleinwater and to form a colored precipitate when the aqueous solution was t ated with alkal ne betamaphtho In addition'to the aromatic amines of the examples, otherprimary aromatic amines can be used to form the diazonium fluosilicates provided they have a -,-NHz group attached to aromatic carbon, i. e. to carbon of an aromatic nucleus. The aromatic ring may contain constituents other than the amine groups provided the constituents do not interfere with the .diazotization reaction. Other aromatic amines useful for forming the The diazonium salt gave the following the substituent groups.

vention are solid, water-soluble, crystalline compoundswhich are stable in the solid state at 25 C. If heated to suificiently high temperatures, they decompose explosively. However, under controlled conditions the diazonium fluosilicates when maintained at a temperature of about 10-20" "C. below the temperature at which explosive decomposition occurs undergo a partial decomposition with evolutionv of gas to 'form=fiuorosubstituted aromaticcompounds as illustrated-by ExampleiI'V. The temperature-of explosivedecompositions varies with different aromatic diazonium.fiuosilicatesdepending in large part on The diazonium ifiuosilicates .can also "be used advantageously in dyeforrning reactions with coupling components where stability of-a'd-iazonium salt atroomtem- .perature is an important .factor.

{The above description and examples are intended to he -'-il1ustrativ.e only. Any modification of. or variation therefrom which conforms to the spirit of the invention is intended to be included withinthe scope of the claim.

:What isclaimedis: 'Benzenedlazonium fluosilicate.

ICHARD HAVEN WILEY.

EE CW 6 2. 5 The fo l win r ie en es ar c r o d i 1Jhe file of t s "patent:

. Nam Date 9. fiQh z ipe M r.- 93 1,813,621 l lentrich July 7, .1931 ,""'T. 'T'.i M a" 2,211,465 I .lewel Aug. 13, 19.40

' FOREIGN PATENTS Number I Country Date 5. 6.353 ee an e a w.opt-.29, 9 3 151,677 Switzerland r Mar. .16. .1932

OTHER REFERENCES Article Diazonium .Qompounds, in Synthetic Organic Chemicals, published by Eastman Kodak 00., vol. V, No. 4, April 1932, pages 1 and 2.

(etc in Div. :43.) 260-141. 

